avoid becoming stunned due to level teleporting

Reported by entrez:  the code to have a hero become stunned for 1..3
turns when going though a level teleporter trap effectively negated
teleport control (except in wizard mode which is probably why this
slipped through).  Make the effect happen after level_tele instead of
before, change it from being stunned to being confused, and only
happen if hero lacks teleport control.

The association between confusion and level teleportation already
exists and this might be just enough of a hint for someone who isn't
aware of that yet to figure it out.  (Probably just wishing thinking.)

Magic portal traversal hasn't changed; it still causes brief stun.

src/teleport.c

@@ -1194,10 +1194,15 @@ level_tele_trap(struct trap* trap, unsigned int trflags)
         You("are momentarily blinded by a flash of light.");
     else
         You("are momentarily disoriented.");
-    make_stunned((HStun & TIMEOUT) + 3L, FALSE);
     deltrap(trap);
     newsym(u.ux, u.uy); /* get rid of trap symbol */
     level_tele();
+    /* magic portal traversal causes brief Stun; for level teleport, use
+       confusion instead, and only when hero lacks control; do this after
+       processing the level teleportation attempt because being confused
+       can affect the outcome ("Oops" result) */
+    if (!Teleport_control)
+        make_confused((HConfusion & TIMEOUT) + 3L, FALSE);
 }
 
 /* check whether monster can arrive at location <x,y> via Tport (or fall) */
@@ -1575,14 +1580,8 @@ mlevel_tele_trap(
             if (trap)
                 seetrap(trap);
         }
-        /*
-         * Commit 6a65b412 stated "Using magic portals and level teleporters
-         * stuns for a few turns. It's taxing to teleport long distances."
-         *
-         * In keeping with that stated intent, restrict the stunning effect.
-         */
-        if (is_xport(tt))
-            mtmp->mstun = 1;
+        if (is_xport(tt) && !control_teleport(mtmp->data))
+            mtmp->mconf = 1;
         migrate_to_level(mtmp, ledger_no(&tolevel), migrate_typ, (coord *) 0);
         return Trap_Moved_Mon; /* no longer on this level */
     }